[Y1-xCax]SrBaCu2.80 (PO4)0.20Oy samples with 0.10≤x≤0.40 were synthesized using the solid state reaction technique. X-ray diffraction patterns show that all the compounds crystallized into a 123 tetragonal structure. The analyses of the structure with Rietveld refinement were made using a model that contain one Cu(2) in a four coordination and not in five coordination as the other 123 tetragonal structures. This fact permits that the Tc increases with Ca concentration. All samples are superconductors as reported previously. © 2001 Elsevier Science B.V.